FIRE BARRIER COMPOSITION

Abstract: A fire barrier composition suitable for high temperature fires is based on a blend of heat-stable solid inorganic material, fusible solid inorganic material and binder matrix material for the composition ingredients. Advantageously the composition, when subjected to fire temperatures, undergoes sequential changes with increasing temperature, comprising: the binder matrix material commences to carbonise or otherwise deteriorate; the fusible inorganic material fuses sufficiently to bond the heat-stable inorganic material in coherence before the binding effect of the matrix material has completely diminished; and then the fusible inorganic material re-solidifies to provide a solid, hard, insulating, fire-barrier compound.

Description: FIRE BARRIER COMPOSITION This invention relates to fire barrier compositions. The invention provides a composition which is capable of forming an advantageous protective barrier against high temperature fires such as burning hydrocarbon oil or gas. The composition of the invention is based on a blend of at least one heat-stable solid inorganic material, at least one fusible solid inorganic material, and at least one binder matrix material for the composition ingredients. The heat-stable solid inorganic material preferably should not decompose at temperatures below about 1000°C, more preferably not below about 1600°C. Suitably also it has a low thermal conductivity (K). If it melts below its decomposition temperature, it should have a high melting point, preferably of at least about 400°C. A suitable material is a ceramic material. Suitably the heat-stable material is in particulate form, whether as powder (e g grindings) or fibre. Additionally or alternatively, the material may be in fabric form when the material lends itself to being produced in that form. By way of example, particle sizes may be in the range 30 to 200 mesh, especially when the composition is to be processed into sheet form. Preferred heat-stable materials include siliceous materials, especially silicates, for example sodium, calcium, magnesium and aluminium silicates, mullite, asbestos and clays e g calcined clay, and silica flour. An example of a suitable non-siliceous heat-stable material is magnesium If desired, a particulate material, e g hollow aluminium silicate particles, may be employed. Such particles may be useful to confer lower density on the composition. The fusible solid inorganic material suitably is a material which melts and then re-solidifies, whereby it bonds to or encapsulates the heat-stable material. Suitably the fusible material is employed in particulate form. Preferably it is employed in fine powder or fibre form and may be of smaller particle size than that of the heat-stable material. For instance it may comprise predominantly particles sized not more than about 200 microns and may have a mean particle size in the range 2 to 70 microns. Preferably the fusible inorganic material melts or commences melting at a temperature of at least about 200°C and suitably it re-solidifies or commences re- solidification at a temperature of, for example, at least about 600°C. For instance, the material may melt at temperatures in the range of about 200°C to 900°C and may re-solidify at temperatures in the range of about 600°C to 1600°C. Preferably the fusion properties of the fusible material are related to the thermal stability of the binder matrix material employed in the composition. Suitably the fusible material should at least commence to melt at a temperature not higher than that at which the binding performance of the matrix material becomes decreased to a level at which it cannot hold the composition ingredients coherently. Accordingly, for instance, when the binder matrix material is an elastomer which becomes effectively degraded or carbonised at about 400°C, the fusible material should become significantly melted at or below that temperature. A preferred fusible material comprises glass particles. Preferably the fusible material comprises a mixture of particles having different melting points, suitably commencing at about 200°C. Such a particle mixture may melt progressively over a temperature range of about 200°C to 900°C, for instance about 350°C to 700°C. The material then re-solidifies above the melting temperature. For instance, re-solidification may commence at a temperature above about 700°C or above about 900°C to form a crystalline solid. It is found that the glassy re-solidified material forms a bond with the heat-stable inorganic material and produces a hard solid fire-barrier compound which is stable at high temperatures such as about 1600°C and which remains solid during subsequent cooling without suffering reversal to particulate form and without significant crack formation. Examples of suitable fusible glass particles are those available under the trade name "Ceepree" ex ICI/Brunner Mond & Company. Examples of other suitable fusible inorganic materials are alumina trihydrate, magnesia trihydrate, zinc hydroxy stannate, hydrated sodium silicate, expandable graphite and mica such as vermiculite. For instance, alumina trihydrate particles may be employed together with or instead of fusible glass particles. It is found that, at temperatures in the range of about 300°C to 600°C, the alumina trihydrate melts by losing water of crystallisation and, at temperatures up to about 1200°C, re-solidifies to bond the heat-stable material into a stable hard fire-barrier compound. This effect may be promoted by the presence of a substance such as zinc hydroxy stannate, for instance about 15 to 20 parts by weight per 100 parts by weight of alumina trihydrate. By employment of such a substance, the temperature at which the solid fire-barrier compound is produced may be lowered, for instance to about 800°C or less. The proportions of heat-stable and fusible inorganic materials in the composition preferably should be greater than those at which the composition would produce a friable non-bound compound when subjected to fire heat and less than those at which the composition would be unprocessable or impractically difficult to process. Preferably these materials are present in a preponderant proportion in relation to the amount of binder matrix material. They may constitute at least 50%, preferably at least 60%, by weight of the composition. By way of example, the composition may contain from about 25% to about 35% of fusible material such as "Ceepree" and from about 30% to about 50% of one or more heat-stable materials. The binder matrix material holds the other composition ingredients in blended form, preferably as a substantially homogenous blend, and facilitates processing and fabrication of the composition. Suitably the binder material is an organic polymer material. A preferred binder material is an elastomeric material, which may be natural or synthetic, cured or uncured. Preferably the elastomeric material has good tack and flexibility over a wide temperature range such as from -35°C to +120°C. Examples of suitable elastomers are polychloroprene rubbers (neoprenes), chlorosulphonated polyethylene (e g "Hypalon") , and blends of polychloroprene with EPDM. One preferred elastomer is polychloroprene rubber having low-temperature flexibility and crystallinity, such as the Neoprene W grades. By way of example, the composition may contain from about 20% to about 30% by weight of elastomer. Alternatively, if desired, a non-elastomeric binder material may be employed, for instance a plastics or resin. If a flexible fire barrier composition is not required, the binder material may be a thermosetting or otherwise hardenable plastics or resin. Such a binder material may be converted into rigid set form either before a fire barrier comprising the composition is utilised or by the effect of the fire heat on the fire barrier in an actual fire situation. When the binder material is an elastomeric material, the composition may contain a plasticizer for the elastomer. The presence of a plasticizer may enable the composition to contain a higher loading of solid inorganic materials and/or may confer higher flexibility without detriment to fire barrier properties, and/or it may aid processability of the composition. If desired, a plasticizer may be employed in place of at least a proportion of the elastomer. Examples of suitable plasticizers are those of the phthalate, phosphate and halogen-containing types. Improved flame-retardance and/or self-extinguishing properties may be conferred on the composition by employing one or more plasticizers of the halogen-containing or phosphate type. By way of example, plasticizer may be present in an amount of up to about 5% by weight of the composition, although a much greater proportion of plasticizer may be employed if desired. The composition may contain one or more other ingredients to confer desired properties without significant detriment to the required fire barrier properties. Examples of additional ingredients include antidegradants e g antioxidants, and pigments e g carbon black. By way of example, the composition may contain up to about 2% by weight of antidegradant(s) and/or up to about 1% by weight of pigment(s). The composition may be prepared by conventional blending methods. For example, when the binder material is an elastomeric material, conventional high-shear milling may be employed, followed by calendering if required. The invention enables the provision of a flexible fire-barrier composition which acts as an environmental barrier and remains flexible for ease of fabrication, assembly and replacement, over a wide atmospheric temperature range of about -35°C to +120°C. In a fire situation, usually the composition functions as an advantageous fire barrier by undergoing the following changes as the temperature increases: the binder matrix material commences to carbonise or otherwise deteriorate; the fusible inorganic material fuses sufficiently to bond the heat-stable inorganic material in coherence before the binding effect of the matrix material has completely diminished; and then the fusible inorganic material re-solidifies to provide a solid, hard, insulating, fire-barrier compound. The composition provides a fire barrier which is effective under intense fire situations up to temperatures such as about 1600°C and which maintains its fire barrier effectiveness on cooling to normal temperatures. The composition may be formed into a sheet or other shape as appropriate for the required fire barrier application or it may be applied by coating directly onto a surface to be fire protected. If desired, it may be made into panels to be assembled together for covering an article or space to be protected. The panels may be secured together, such as in abutment, for instance by means of fire-resistant thread e g filament comprising stainless steel. The composition may be employed as a component of a composite material. For instance, the composition may be formed into a composite with one or more fire- resistant fibrous components which may provide reinforcement for handling and fabrication. One form of such a composition is a laminate of the composition with fire-resistant fabric, for example a layer of the composition having a fire-resistant open- or closed- weave fabric sheet attached to one or each face. The composition may be attached to a fabric sheet by, for example, calendering or adhesive bonding. One advantageous fabric is a high melting point glass cloth. When such a cloth is located on the fire-exposure side of the composition it may protect against premature degradation of the binder matrix material. Additionally or alternatively, the composition may be formed into a composite with one or more heat- insulation components, for instance as a laminate of the composition (reinforced or not) with one or more layers of heat-insulation material. In use as a fire barrier, such a laminate normally should be oriented so that the composition layer is nearer the fire source. It is found that even a quite thin layer of the composition can provide an advantageous fire barrier. The chosen composition thickness may be influenced by physical factors such as the tensile strength required to resist the force of a jet fire and/or the practical weight and thickness limitations for ease of fabrication and assembly of the fire barrier. An example of an efficient fire barrier thickness of the composition is about 3 mm. The composition is capable of providing fire barriers for intense fire situations, for instance in jet fire situations which may occur in the oil and petroleum industries. For example, the composition may be formed into protective covers for valve actuators on oil rigs. If required, a heat-insulation material may be located between the cover and the surface to be protected.

Claims: CLAIMS : 1. Fire barrier composition based on a blend of: (a) heat-stable solid inorganic material; (b) fusible solid inorganic material; and (c) binder matrix material for the composition ingredients. 2. Composition according to Claim 1 wherein the fusible material comprises material which, when heated, melts and then re-solidifies to bond to the heat-stable material. 3. Composition according to Claim 2 wherein the fusible material commences melting at a temperature not higher than that at which the binding performance of the matrix material is decreased to a level at which it cannot hold other composition ingredients coherently. 4. Composition according to Claim 2 or 3 wherein the fusible material commences melting at a temperature of at least about 200"c and commences re-solidifying at a temperature of at least about 600 * C. 5. Composition according to any of the preceding Claims wherein the fusible material is in fine particulate form. 6. Composition according to any of the preceding Claims wherein the fusible material comprises a mixture of particles having different melting points. 7. Composition according to any of the preceding Claims wherein the fusible material comprises glass particles. 8. Composition according to Claim 7 wherein the fusible material comprises a glass particle mixture available under the trade name 'Ceepree'. 9. Composition according to any of the preceding Claims wherein the fusible material comprises alumina trihydrate particles. 10. Composition according to Claim 9 which comprises additionally zinc hydroxy stannate. 11. Composition according to any of the preceding Claims wherein the total amount of the heat-stable material and the fusible material is at least 50% by weight of the composition. 12. Composition according to any of the preceding Claims wherein the heat-stable material comprises siliceous material in particulate or fabric form. 13. Composition according to Claim 12 wherein the siliceous material comprises metal silicate. 14. Composition according to any of the preceding Claims wherein the binder matrix material comprises elastomeric material which is flexible over the temperature range -35 β C to +120 * C. 15. Composition according to any of the preceding Claims wherein the binder matrix material comprises Neoprene W grade polychloroprene rubber. 16. Composition according to any of the preceding Claims wherein the amount of binder matrix material is from about 20% to about 30% by weight of the composition. 17. Composition according to any of the preceding Claims which includes a plasticizer such as halogen-containing, phosphate or phthalate plasticizer. 18. Composition according to any of the preceding Claims which, when subjected to fire temperatures, undergoes sequential changes with inceasing temperature, comprising: the binder matrix material commences to carbonise or otherwise deteriorate; the fusible inorganic material fuses sufficiently to bond the heat- stable inorganic material in coherence before the binding effect of the matrix material has completely diminished; and then the fusible inorganic material re-solidifies to provide a solid, hard, insulating, fire-barrier compound. 19. Composition substantially as described herein. 20. Fire barrier comprising a composition according to any of the preceding Claims.

Inventors: GANENDRAN ARASAPILLAI NADARAJA, NEAVE JOHN, GANENDRAN, ARASAPILLAI, NADARAJAH, NEAVE, JOHN
Applicants: BTR PLC, GANENDRAN ARASAPILLAI NADARAJA, NEAVE JOHN, GANENDRAN, ARASAPILLAI, NADARAJAH, NEAVE, JOHN
Application year: 1994
Main classification: C09K21
IPC codes: C08K3, C09K21